Electrical connectors have long been used in electrical and electronic equipment to interconnect various parts of systems and equipments through multiconductor cables either within or between the enclosures housing the functional parts or subparts. Individual circuit components and functional elements and assemblies have become drastically miniaturized because of the availability of relatively inexpensive etched circuit component boards and semiconductor integrated circuits. As the number of circuit elements and functions embodied in each self-contained component increased, the number of electrical connections into and out of each component likewise increased. At the same time, the space available for such connections became severely limited as the size of the multifunctional components shrank.
Such circumstances and repair and replacement considerations have caused the industry to abandon many "hand wiring" techniques in favor of separable plug and socket connector techniques for component and subsystem interconnections. Progressing miniaturization has resulted in demand for smaller and smaller connectors with a steadily increasing number of individual connective elements or contacts. Connectors with up to 450 or more contact pins mounted on 0.050 inch centers on a base only 1.2 of an inch square and less than +3/16 inch thick are common. In a system of such size, the plug element pins may be about 0.020 inches in diameter and the pin receptacle elements may be about 0.040 inches outside diameter with openings of appropriate size to accept the pins with good electrical contact.
As can easily be understood, difficulties arise when it is attempted to insert the pins of the male pin or plug half of the connector quickly into the receptacle contacts of the female socket or receptacle half of the connector. The problem of exactly orienting the pins of plug base with the receptacle contacts of the socket base is aggravated by even a single pin being slightly out of alignment.
Obvious solutions to the insertion problems such as beveling the receptacle contact opening have proved unsatisfactory. The pins often "stick" in the conical walls of the openings and deform even more preventing full insertion of the plug end of the socket.